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[SVE] Fold svrev(svrev(v)) to v.

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gcc/ChangeLog:
	* tree-ssa-forwprop.cc (is_combined_permutation_identity): Try to
	simplify two successive VEC_PERM_EXPRs with same VLA mask,
	where mask chooses elements in reverse order.

gcc/testsuite/ChangeLog:
	* gcc.target/aarch64/sve/acle/general/rev-1.c: New test.
This commit is contained in:
Prathamesh Kulkarni 2023-04-25 01:12:28 +05:30
parent ad1816a8ab
commit f0eabc52c9
2 changed files with 33 additions and 0 deletions
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12
gcc/testsuite/gcc.target/aarch64/sve/acle/general/rev-1.c Normal file
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@ -0,0 +1,12 @@
/* { dg-do compile } */
/* { dg-options "-O3 -fdump-tree-optimized" } */
#include <arm_sve.h>
svint32_t f(svint32_t v)
{
return svrev_s32 (svrev_s32 (v));
}
/* { dg-final { scan-tree-dump "return v_1\\(D\\)" "optimized" } } */
/* { dg-final { scan-tree-dump-not "VEC_PERM_EXPR" "optimized" } } */

21
gcc/tree-ssa-forwprop.cc
View file

@ -2541,6 +2541,27 @@ is_combined_permutation_identity (tree mask1, tree mask2)
gcc_checking_assert (TREE_CODE (mask1) == VECTOR_CST
&& TREE_CODE (mask2) == VECTOR_CST);
/* For VLA masks, check for the following pattern:
v1 = VEC_PERM_EXPR (v0, ..., mask1)
v2 = VEC_PERM_EXPR (v1, ..., mask2)
-->
v2 = v0
if mask1 == mask2 == {nelts - 1, nelts - 2, ...}. */
if (operand_equal_p (mask1, mask2, 0)
&& !VECTOR_CST_NELTS (mask1).is_constant ())
{
vec_perm_builder builder;
if (tree_to_vec_perm_builder (&builder, mask1))
{
poly_uint64 nelts = TYPE_VECTOR_SUBPARTS (TREE_TYPE (mask1));
vec_perm_indices sel (builder, 1, nelts);
if (sel.series_p (0, 1, nelts - 1, -1))
return 1;
}
}
mask = fold_ternary (VEC_PERM_EXPR, TREE_TYPE (mask1), mask1, mask1, mask2);
if (mask == NULL_TREE || TREE_CODE (mask) != VECTOR_CST)
return 0;